DWI 及 SWI 在急性出血性脑梗死的临床应用

【目的】探讨急性出血性脑梗死在磁共振弥散加权成像(DWI)及磁敏感加权成像(SWI)上的影像表现特点,从而达到早期、明确诊断急性出血性脑梗死的目的。【方法】回顾性分析15例临床明确诊断为急性出血性脑梗死患者在 DWI 和 SWI 的信号表现以及常规 MRI 的信号表现及首次头部 CT 的表现,将前者的信号改变与后两者进行对比观察,从而发现急性出血性脑梗死在 DWI 和 SWI 像上的信号特点。【结果】15例急性出血性脑梗死在常规头部 CT 均表现为等密度,与正常脑组织密度差别不大,难以明确诊断;在常规 MRI影像上表现有一定差异：T1加权成像(T1 WI)上所有病灶均呈等或稍低信号,T2加权成像(T2 WI),上均呈等或稍高信号,FLAIR 影像上均呈等或稍高信号,病灶边界显示欠清,很容易误诊为缺血性脑梗死;但在 DWI及表观扩散系数(ADC)图上表现有较明显的差异：在 DWI 影像上呈混杂高信号,ADC 影像上呈混杂低信号,与急性缺血性脑梗死信号改变不同;SWI 对梗死灶内的少量出血显示为特征性低信号影,校正相位影像上呈混杂高信号,急性缺血性脑梗死在 SWI 影像上无明显异常信号改变。【结论】DWI 及 ADC 对急性出血性脑梗死有一定诊断价值,SWI 对急性出血性脑梗死灶内少量出血的诊断敏感性高,两者有机结合对明确诊断急性出血性脑梗死具有很高的临床应用价值。     

磁敏感加权成像在中枢神经系统疾病的应用

目的 探讨磁敏感加权成像(SWI)在中枢神经系统疾病的临床应用价值.方法 脑部病变患者35例进入研究.其中海绵状血管瘤6例,脑梗死15例,脑肿瘤10例,静脉畸形2例,静脉窦血栓2例.对患者行常规T2WI、T1WI、SWI序列、MRA及增强T1WI.分析SWI序列较其他序列对显示小的出血灶、小静脉及含铁血黄素、钙化等顺磁性物质的优势.结果 对于海绵状血管瘤,SWI能鉴别出血与血管,发现更多的小病灶.对于静脉畸形,能够发现更多的细小静脉向大静脉引流.对于急性脑梗死,SWI可发现小的出血灶.对于脑肿瘤,SWI可显示出小的引流静脉.对于静脉窦血栓,SWI可清楚显示深部引流静脉及脑表面扩张的静脉网.结论 与常规MRI及MRA检查相比,SWI对低流量血管畸形及血管瘤、多发细小出血的显示、脑肿瘤的血管评价、静脉窦血栓形成后深部静脉的扩张及早期并发出血以及脑梗死并发出血等病变的显示具有明显的优越性,并能提供病变与正常组织的相位对比改变, 对提高中枢神经系统疾病的正确诊断具有较大的帮助.     

磁共振弥散加权成像在急性脑梗死诊断中的应用价值

目的探讨磁共振弥散加权成像在急性脑梗死诊断中的应用价值。方法选取疑似急性期、超急性期脑血管病患者66例为研究对象,全部患者均给予磁共振常规弥散加权扫描、水抑制序列扫描和常规T1WI、T2WI扫描,对梗死灶和对侧相应部分正常脑组织的表现弥散系数(ADC)值进行测定。结果 66例患者中超急性期脑梗死9例,急性期脑梗死57例;急性期和超急性期脑梗死患者在磁共振弥散加权成像(DWI)上呈高信号,T2WI上呈部分稍高信号或等信号,ADC图上呈低信号。梗死灶ADC值显著低于对侧相应部位正常脑组织的ADC值,差异有统计学意义(P<0.05)。结论在对急性脑梗死患者进行检查诊断时,磁共振弥散加权成像的诊断敏感性较高,采用弥散加权扫描能有效区分多发脑梗死中的新旧病灶,进而为临床治疗方案的制定提供科学依据。     

磁共振弥散加权成像诊断急性脑梗死的价值

目的评价磁共振弥散加权成像(DWI)和表观扩散系数(ADC)图在急性脑梗死诊断中的应用价值。方法回顾性分析41例急性脑梗死患者的MRI检查资料,其中超急性期(<6 h)4例,急性期(6~72 h)37例,均行磁共振常规T1WI、T2WI、Dark-fluid及DWI检查。结果 DWI显示病灶、病灶边界以及范围均优于常规T1WI、T2WI、Dark-fluid像;41例在DWI像上均表现为异常高信号,ADC图上表现为低信号。结论 DWI结合ADC图对诊断急性脑梗死具有很高的准确性和敏感性,能发现常规T1WI、T2WI、Dark-fluid像上不能发现的超急性期脑梗死,DWI与T2WI、ADC图结合能判断不同时期脑梗死。     

磁敏感成像序列在急性大面积脑梗死并发出血中的应用

目的：探讨3.0 T MR磁敏感加权成像（SWI）对检出急性大面积脑梗死所并发出血病变（ACIH）的诊断和鉴别诊断价值。材料与方法对67例ACIH患者行MRI扫描,比较T1WI、T2WI、FLAIR和DWI等常规序列与SWI序列对ACIH中出血灶检出率的差异。结果67例ACIH中,常规序列检出伴有出血的病例59例,检出率88.06%;SWI序列检出伴有出血的病例67例,检出率100%;SWI序列对ACIH的检出率高于常规序列,两者差异具有显著性意义。常规序列未检出的隐匿性出血灶均表现为与脑梗死一致的信号影,而在SWI序列表现为明显的低信号影。SWI所显示脑梗死中出血灶的平均面积[（4.32±0.67） cm2]均大于MR常规序列所显示的平均面积[（2.87±0.48） cm2],两者差异有显著性意义。结论 SWI序列较MRI常规序列能准确检出ACIH中更多的出血性病变,应作为大面积脑梗死检查的补充序列。     

磁敏感加权成像对脑肿瘤诊断价值初探

目的探讨磁敏感加权成像（SWI）对脑肿瘤的诊断价值。方法41例脑肿瘤患者行常规横断位（T1WI、T2WI）和横断位SWI检查,其中30例同时行横断位T1WI和SWI增强扫描。观察SWI图像上肿瘤显示、瘤周水肿、肿瘤出血、肿瘤钙化及肿瘤静脉等5个项目,并对所有项目进行评分（0～3）,采用析因设计的方差分析及LSD多重检验。结果SWI图像上,脑膜瘤、低级别星形细胞瘤表现为等或稍高信号;复发性脑膜瘤、多数高级别星形细胞瘤及脑转移瘤实性成分表现为稍低信号。脑膜瘤内部新生血管较少,周围静脉呈弧形受压改变;低级别星形细胞瘤肿瘤静脉稀疏、散在分布;复发性脑膜瘤、高级别星形细胞瘤及转移瘤内部静脉血管丰富,瘤周静脉表现各异。相位图上肿瘤钙化以低信号为主,而且钙化灶最外层表现为高信号;出血灶信号与之相反。瘤周水肿表现为高信号。在肿瘤出血、肿瘤钙化及肿瘤静脉显示方面,SWI与T1WI、T2WI评分结果差别具有统计学差异（P〈0．01）;在瘤周水肿显示方面,SWI与T2WI评分结果差别无统计学意义;在肿瘤显示方面,CE-SWI及CE-T1WI与其他序列评分结果的差别有统计学意义（P〈0．01）。结论SWI在显示肿瘤的一般影像特征的基础上突出显示肿瘤静脉、出血代谢物和钙化灶,提供不同于常规MRI序列的肿瘤内部病理信息,相位图像有助于肿瘤出血与钙化的鉴别。     

磁共振磁敏感加权成像在出血性脑梗死诊断中的应用价值

目的:观察磁共振磁敏感加权成像(Susceptibility Weighted Imaging,SWI)在出血性脑梗死诊断中的应用价值。方法:选择2015年2月-2017年1月在我院检查的36例出血性脑梗死患者,为患者分别进行磁敏感加权成像(SWI)、弥散加权成像(DWI)及常规MRI扫描,对比三种不同诊断方法对出血性脑梗死患者检出率及出血灶数量的显示情况。观察SWI序列显示脑梗死区域及周围微出血灶数量情况,以及脑梗死灶内静脉血管变化情况。结果:磁共振磁敏感加权成像对出血性脑梗死的检出率和出血灶数量的显示明显优于弥散加权成像及常规MRI扫描的序列,数据差异具有统计学意义(p0.05);在所有患者中,发现12例患者脑梗死灶区域之外存在微出血灶,有19例患者脑梗死灶内的小静脉血管分支明显减少,6例患者其血管发生增多、增粗或扭曲的情况。结论:磁共振磁敏感加权成像在出血性脑梗死诊断中具有良好的应用价值,其诊断阳性率明显优于弥散加权成像及常规MRI序列,可早期发现脑梗死中的出血灶,值得临床应用及推广。     

SWI对急性脑梗死伴出血性转化患者诊断准确率及出血灶检出率的影响

目的:探讨磁敏感加权成像(Susceptibility weighted imaging,SWI)在急性脑梗死伴出血性转化诊断中的应用价值。方法:收集我院2017年8月-2019年8月行磁共振成像(Magnetic Resonance Imaging,MRI)+DWI+SWI检查证实为急性脑梗塞治疗后伴有出血性转化的40例患者的临床资料,以常规MRI序列+DWI+SWI诊断为"金标准",分析SWI诊断出血性转化的准确率,记录分析SWI检查对出血灶的检出率。结果:SWI检查对急性脑梗死伴出血性转化的诊断准确率为89.16%,对出血灶的检出率为100.00%。结论:SWI检查对急性脑梗死治疗后伴出血性转化的诊断准确率与对出血灶的检出率均处于理想水平,具有较高的临床应用价值。     

肝脏恶性肿瘤扩散加权成像与T2加权成像对比研究

目的比较肝脏扩散加权成像(DWI)和T2WI反映肝脏恶性肿瘤扩散特征、病理特征及肿瘤范围的价值.方法回顾性研究肝脏恶性肿瘤44例48灶(肝细胞癌30例30灶,肝转移瘤10例14灶,胆管细胞癌4例4灶),比较DWI与T2WI图像液体(脑脊液,胆囊胆汁)和肝脏恶性肿瘤的信号,肿瘤/肝脏信号强度比(SIR),对比噪声比(CNR)以及肿瘤范围,测量肿瘤表观扩散系数(ADC)值.结果在b=600 s/mm2的图像中,所有病例的脑脊液均显示为低信号.肝脏恶性肿瘤多表现为高信号,其信号分布特征与T2WI不同;肿瘤的信号强度和瘤/肝SIR,DWI与T2WI不相关;DWI信号强度与ADC值呈负相关.DWI的病灶对比噪声比高于T2WI,二者差异有显著性.DWI显示病灶范围与T2WI差异无显著性.结论b=600 s/mm2的肝脏DWI图像受T2穿透效应影响较小,能够较好地反映肝脏恶性肿瘤的扩散特征.DWI肿瘤对比噪声比更高,有助于病灶边界的确定.DWI反映的肝脏恶性肿瘤的扩散特征,可作为其影像学特征之一.     

磁敏感加权成像对脑梗死的诊断价值

目的探讨磁敏感加权成像(SWI)对脑梗死的诊断价值。材料与方法30例患者在3.0 T MR成像系统行常规MRI、扩散加权成像(DWI)和SWI,20例同时行MR血管成像(MRA),19例行静脉注射Gd-DTPA增强扫描。将SWI采集的原始数据传输到GE AW4.4工作站离线处理,得到校正相位图(CPI)和磁化率加权图。手动测量脑梗死区及水肿区与正常对照区的CP值,采用t检验进行比较,以P0.05为差异有统计学意义。结果 30例脑梗死在DWI上表现为高信号,15例MRA图像可见大脑前、中、后动脉不同程度的狭窄或闭塞。5例SWI上可见大脑中动脉内血栓,与MRA图像显示的区域相一致;21例SWI上病灶内合并出血,CT发现9例,T1WI仅发现2例;SWI显示15例梗死区静脉血管增多,6例静脉血管分布正常,9例静脉血管分布减少。梗死区与正常对照区的CP值分别为-0.021±0.006、-0.006±0.005,差异有统计学意义(t=-2.359,P0.05);水肿区与正常对照区的CP值分别为-4.853±0.005、-1.868±0.003,差异有统计学意义(t=-2.172,P0.05)。结论 SWI对脑梗死急性期并发的出血及静脉血管分布的显示具有常规MRI无可替代的优势,对脑梗死急性期治疗具有重要的指导作用;并且校正相位图可以进行定量分析。     

Whole-body magnetic resonance imaging

Whole-body magnetic resonance imaging is a fast and accurate modality for the detection of disease throughout the entire body. Technical improvements including the availability of different high image quality MR sequences, the remote movement of the imaging table, and the use of specialized surface coils have rendered whole-body screening with MRI a feasible method. In this article we describe underlying techniques and report on first clinical experiences of whole-body magnetic resonance imaging as a staging and screening method. Furthermore, advantages and limitations compared with whole-body imaging based on computed tomography are discussed.     

Breast magnetic resonance imaging

Breast MRI is becoming an important tool for the improved management of breast cancer. The technical attributes of high contrast, high-resolution breast MRI acquisitions are summarized. The fundamentals of image interpretation are outlined, including lesion enhancement, morphological features, and extent categories. The indications for breast MRI include compromised mammography, staging of disease within the breast and adjacent structures, difficult histology, and other special diagnostic situations. Patients with compromised mammography include previous surgery, radiographically dense breasts, and silicone augmentation. The improved determination of disease extent aids in the management of breast conservation treatment. Certain lesions, particularly lobular carcinoma and ductal carcinoma in situ, can be better managed with the information available with breast MRI. Other potential indications are also discussed, including patients presenting with positive axillary nodes and no known primary, women with a high risk of malignancy, and recently postoperative breasts with positive margins. The need for MRI stereotaxis is reviewed, with indications and potential solutions. The potential future roles for MRI-directed interstitial hyperthermia are outlined.     

Three-dimensional magnetic resonance imaging

Three-dimensional surface reconstruction images of the heart and great vessels can be produced from contiguous sequences of ECG-triggered MR scans in patients with congenital heart disease. The methods allow separation of the epi- and endocardial surfaces and definition of the enclosed blood volumes on a slice-by-slice basis. Surface reconstruction images have value in communicating the results of MR examinations to clinicians in cases where cardiac morphology is unusually complex; in depicting intracardiac defects, size, and location; and in aiding the study of pulmonary venous drainage. This method can be practical in studying cardiac morphologic abnormalities and especially in planning cardiac surgery.     

Intravascular magnetic resonance imaging

The purpose of this article is to review the current state of the art with respect to intravascular magnetic resonance imaging, including intravascular coils, their implementation for plaque identification and characterization, and strategies for future approaches to coronary imaging and other cardiovascular applications.     

Fetal magnetic resonance imaging

Ultrafast magnetic resonance imaging (MRI) sequences have changed the use of MRI to evaluate fetal abnormalities. Currently, the best application is the evaluation of suspected brain abnormalities found on ultrasound. MRI differentiates the various types of fetal ventriculomegaly. Superior posterior fossa visualization allows differentiation of Dandy-Walker malformation from a large cisterna magna. Anomalies of the corpus callosum can be seen. MRI also is valuable in the evaluation of fetal giant neck masses for planning delivery of the baby and surgery for life-threatening airway obstruction. In the chest, MRI differentiates masses such as diaphragmatic hernia, cystic adenomatoid malformation, and sequestration, and it aids in planning fetal surgery because MRI directly visualizes the position of the lung, liver, and bowel.